Pulmonary arteriovenous fistula

Definition

Pulmonary arteriovenous fistula is an abnormal connection between an artery and vein in the lungs. As a result, blood passes through the lungs without receiving enough oxygen.

Alternative Names

Arteriovenous malformation - pulmonary

Causes

Pulmonary arteriovenous fistulas are usually the result of abnormal development of the blood vessels of the lung. Most occur in people with hereditary hemorrhagic telangiectasia (HHT). These people often have abnormal blood vessels in many other parts of the body.

Fistulas also can be a complication of liver disease or lung injury, although these causes are much less common.

Symptoms

Many people have no symptoms. When symptoms occur, they can include:

• Bloody sputum
• Difficulty breathing
• Difficulty exercising
• Nosebleeds
• Shortness of breath with exertion
• Chest pain 
• Blue skin (cyanosis)
• Clubbing of the fingers

Exams and Tests

The health care provider will examine you. The exam may show:

• Abnormal blood vessels (telangiectasias) on the skin or mucous membranes
• Abnormal sound, called a murmur when a stethoscope is placed over the abnormal blood vessel
• Low oxygen when measure with a pulse oximeter

Tests that may be done include:

• Arterial blood gas, with and without oxygen (usually oxygen treatment does not improve the arterial blood gas as much as expected)
• Complete blood count (CBC)
• Chest x-ray
• Chest CT scan
• Echocardiogram with bubble study to check the function of the heart and assess for presence of a shunt
• Lung function tests
• Perfusion radionuclide lung scan to measure breathing and circulation (perfusion) in all areas of the lungs
• Pulmonary arteriogram to view the lung arteries

Treatment

A small number of people who have no symptoms may not need treatment. For most people with fistulas, the treatment of choice is to block the fistula during an arteriogram (embolization).

Some people may need surgery to remove the abnormal vessels and nearby lung tissue.

When arteriovenous fistulas are caused by liver disease, the treatment is a liver transplant.

Outlook (Prognosis)

The outlook for people with HHT is not as good as for those without HHT. For people without HHT, surgery to remove the abnormal vessels usually has a good outcome, and the condition is not likely to return.

For people with liver disease as a cause, prognosis depends on liver disease.

Possible Complications

Complications may include:

• Bleeding in the lung
• Stroke due to blood clot that travels from the lungs to the arms, legs, or brain (paradoxical venous embolism)
• Infection in the brain or heart valve, especially in patients with HHT

When to Contact a Medical Professional

Call your provider if you often have nosebleeds or difficulty breathing, especially if you also have a personal or family history of HHT.

Prevention

Because HHT is often genetic, prevention is not usually possible. Genetic counseling may help in some cases.

References

Shovlin CL, Jackson JE. Pulmonary vascular abnormalities. In: Broaddus VC, Mason RJ, Ernst JD, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 61.

Stowell J, Gilman MD, Walker CM. Congenital thoracic malformations. In: Shepard JO, ed. Thoracic Imaging: The Requisites. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 8.

Webb GD, Smallhorn JF, Therrien J, Redington AN. Congenital heart disease in the adult and pediatric patient. In: Zipes DP, Libby P, Bonow RO, Mann DL, Tomaselli GF, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 11th ed. Philadelphia, PA: Elsevier; 2019:chap 75.